The CIA’s Project AZORIAN was a highly secret mission to recover a sunken Soviet submarine during the Cold War. The operation involved using the Hughes Glomar Explorer, a ship believed to be for deep-sea mining, to search for the submarine. Despite facing many challenges, the CIA successfully lifted a portion of the submarine from the ocean floor, recovering bodies of Soviet submariners, and holding a military burial at sea. However, a theft of secret documents and subsequent media exposure led to the project being exposed, forcing the cancellation of further recovery operations. The Glomar Explorer’s secretive career came to an end, but it remains an engineering marvel of the Cold War era.
https://www.cia.gov/legacy/museum/exhibit/project-azorian/